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firmware: imx-dsp: Export functions to request/free channels

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In order to save power, we only need to request a channel
when the communication with the DSP active.

For this we export the following functions:
	- imx_dsp_request_channel, gets a channel with a given index
	- imx_dsp_free_channel, frees a channel with a given index

Notice that we still request channels at probe to support devices
that do not have PM callbacks implemented.

More explanations about why requesting a channel has an effect
on power savings:
 - requesting an mailbox channel will call mailbox's startup
   function.
 - startup function calls pm_runtime_get_sync which increments device
   usage count and will keep the device active. Specifically, mailbox
   clock will be always ON when a mailbox channel is requested.

Signed-off-by: Daniel Baluta <daniel.baluta@nxp.com>
Reviewed-by: Paul Olaru <paul.olaru@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>
This commit is contained in:
Daniel Baluta 2020-11-11 13:11:18 +02:00 committed by Shawn Guo
parent 046326989a
commit 23d89aa0c2
2 changed files with 35 additions and 0 deletions
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25
drivers/firmware/imx/imx-dsp.c
View File

@ -60,6 +60,31 @@ static void imx_dsp_handle_rx(struct mbox_client *c, void *msg)
}
}
struct mbox_chan *imx_dsp_request_channel(struct imx_dsp_ipc *dsp_ipc, int idx)
{
struct imx_dsp_chan *dsp_chan;
if (idx >= DSP_MU_CHAN_NUM)
return ERR_PTR(-EINVAL);
dsp_chan = &dsp_ipc->chans[idx];
dsp_chan->ch = mbox_request_channel_byname(&dsp_chan->cl, dsp_chan->name);
return dsp_chan->ch;
}
EXPORT_SYMBOL(imx_dsp_request_channel);
void imx_dsp_free_channel(struct imx_dsp_ipc *dsp_ipc, int idx)
{
struct imx_dsp_chan *dsp_chan;
if (idx >= DSP_MU_CHAN_NUM)
return;
dsp_chan = &dsp_ipc->chans[idx];
mbox_free_channel(dsp_chan->ch);
}
EXPORT_SYMBOL(imx_dsp_free_channel);
static int imx_dsp_setup_channels(struct imx_dsp_ipc *dsp_ipc)
{
struct device *dev = dsp_ipc->dev;

10
include/linux/firmware/imx/dsp.h
View File

@ -55,6 +55,9 @@ static inline void *imx_dsp_get_data(struct imx_dsp_ipc *ipc)
int imx_dsp_ring_doorbell(struct imx_dsp_ipc *dsp, unsigned int chan_idx);
struct mbox_chan *imx_dsp_request_channel(struct imx_dsp_ipc *ipc, int idx);
void imx_dsp_free_channel(struct imx_dsp_ipc *ipc, int idx);
#else
static inline int imx_dsp_ring_doorbell(struct imx_dsp_ipc *ipc,
@ -63,5 +66,12 @@ static inline int imx_dsp_ring_doorbell(struct imx_dsp_ipc *ipc,
return -ENOTSUPP;
}
struct mbox_chan *imx_dsp_request_channel(struct imx_dsp_ipc *ipc, int idx)
{
return ERR_PTR(-EOPNOTSUPP);
}
void imx_dsp_free_channel(struct imx_dsp_ipc *ipc, int idx) { }
#endif
#endif /* _IMX_DSP_IPC_H */